I connect to a microtik server distributing internet , I must edit the mac adress to match that in the microtik server to give me internet the original adress of the interface is that one in nm-tool command output , i need to change it to the following adress 00:1e:8c:15:91:55i used the ifconfig ifconfig hw ether command and the package macchanger-gtk to change the mac adress .but in network manager it doesnt change it stay the same although it change when displaying status of eth0 with ifconfig command .

No you are trying to use both. Ifconfig amd macchanger are command line tools but you are expecting NM to take account of the changes. As I said, you either use command line networking or NM, not both. If you want to use command line tools, remove NM.

[Edit] your original post and add [SOLVED] once your question is resolved.

“The people are my God” stressing the factor determining man’s destiny lies within man not in anything outside man, and thereby defining man as the dominator and remoulder of the world.

i don't care NM reflect mac change or not , what i am care of is to get the internet working ,please tell me detailed steps to get y internet working am still new to linux , and you are our expert here .